Method of making filamentous mats



Sept. 19, 1967 R. L. JACKSON, JR METHOD OF MAKING FILAMENTOUS MATS FiledDec. 11. 1963 .IFIGJ INVENTOR. ROBERT L. JACKSON,JR.

ATTORNEY United States Patent 3,342,658 METHOD OF MAKING FILAMENTOUSMATS Robert L. Jackson, Jr., Louisville, Ky., assiguor to American AirFilter Company, Inc., Louisville, Ky., a corporation of Delaware FiledDec. 11, 1963, Ser. No. 329,714 6 Claims. (Cl. 156-174) This inventionrelates to a method of making filamentous mats of the type commonly usedfor decorative purposes in plastic sheet material.

The invention is concerned with, and has as one object, the provision ofa method for making a decorative mat in which the decorative characterprimarily derives from separate strata of the mat presenting distinctlydifferent filament patterns.

Another object is the provision of a method which may be readilypracticed with existing apparatus and utilizing recognized glass fiberhandling techniques.

It is well known to make a filamentous mat in the following manner:building up a cylindrical compact mat by feeding continuous filaments toa rotatingdrum from a filament feeder which is reciprocated back andforth along a path parallel to the axis of the drum; slitting the matalong an axial line and unwrapping it from the drum to form a planarmat; and stretching the mat in a direction transverse to the general layof the filaments. The binder which holds the filaments together in thefinal mat is applied while the filaments are being wound upon the drumand/ or after'the mat has been stretched.

In accordance with my invention the foregoing conventional process islargely followed, but with the important difference of applying a binderto only a selected stratum of the mat during winding, and winding theremainder of the filaments to form a stratum of distinct depth withoutthe application of binder. When the removed mat is stretched, thestretching characteristics of the mat as a whole is influenced by thestretching characteristics of each of the diverse strata. However, thepattern of the filaments in the stretched mat corresponding to thebinder wetted stratum presents a distinctly different appearance thanthe pattern of filaments corresponding to the stratum wound in theabsence of binder. Thus the invention provides a very simple method offorming a mat in which a decorative pattern of one particular characteroverlies a pattern of another distinct character. The winding step ofthe process may be carried out without interruption with the applicationof the binder during the winding step being simply stopped at theappropriate time. Hence, a product is formed which gives the appearanceof being laminated without any requirement, in fact, of a separatelaminating step.

While the invention is primarily intended for use in making decorativefilamentous mats and will be described in this connection, it will beappreciated by those skilled in the art that a mat made in accordancewith the invention may also serve reinforcing and perhaps other purposesas well.

The invention will be explained in connection with the accompanyingdrawing wherein:

FIGURE 1 is a partly diagrammatic front elevational view of apparatusfor winding a cylindrical compact mat;

FIGURE 2 is a partly diagrammatic side elevational view of the apparatusof FIGURE 1;

FIGURE 3 is a diagrammatic side elevational view of apparatus usedduring the stretching and further treatment of a mat according to theinvention; and,

3,342,658 Patented Sept. 19, 1967 "ice FIGURE 4 is a representation ofthe appearance of two strata, purposely separated, of a mat madeaccording to the invention.

Referring to FIGURES 1 and 2, a cylindrical compact mat according to theinvention is made by feeding a plurality of glass fiber filaments 2,issuing from a glass fiber producing furnace 4, onto the surface of arotating drum 6. The furnace 4 is driven in a reciprocating path axiallyalong, and back and forth between the ends of the drum. The drivingmeans (not shown) for effecting such reciprocating movement may be ofthe type which provides a substantially uniform furnace traverse speedbetween end reversal points, but preferably is of the type disclosed inmy US. Patent 2,798,531 which provides a furnace traversing speed whichis varied in a cyclically repetitive pattern between maximum and minimumspeed value one or more times during each traverse. The drum is rotateda multiplicity of times during each traverse of the furnace so that thesuccessive layers of compact mat built up on the drum duringcorrespondingly suc cessive traverses will each contain a multiplicityof helical turns of filaments extending continuously from one end of thedrum to the other. It will be appreciated that with this arrangement,the filaments of adjacent layers of the compact mat lie in crossingrelationship.

The binder is applied to the filaments of a selected stratum of thecompact mat as it is being built up by a spray applicator 8 which isarranged to periodically traverse the drum in an axial direction. Thedrum-applied binder selected preferably should be of the type whichretains substantial flexibility until the subsequent stretching of themat takes place. One suitable binder i a resilient polyester resinidentified as InterChem 1390 manufactured by InterChemical Corp.

The currently preferred mat according to the invention is made byapplying the binder to only the inner or underlying stratum of thecompact mat, and then termimating the binder application while an outeror overlying stratum is wound on the drum. This reduces the chance thatin the reverse situation the binder being applied during the formationof a wet stratum over a dry stratum will penetrate into the filaments ofthe dry stratum.

In most instances it is desirable to highlight the differences inpattern between the binder-wetted filaments of the one stratum and thedry filaments of the other stratum. To this end the binder materialapplied during the winding step has a pigment and/or dye, which iscompatible with the binder, added to it.

After a cylindrical compact mat of desired thickness is built up uponthe drum, it is slit axially, removed from the drum, and laid out flaton a supporting table 10 to form a planar compact mat 12 (FIG. 3). Tofacilitate removal of the mat from the drum without disturbing thefilament arrangement, one paper sheet is wrapped on the drum beforefilament winding, and another after winding.

The planar compact mat 12 is then stretched or elongated in a directiongenerally transverse: to the lay of the filaments by pulling filamentsextending along the one edge of mat in that direction. After the initialedge filaments are pulled away from the remainder of that mat, thesuccessively adjacent filaments follow along in succession to ultimatelyform the stretched mat, which is perhaps equally well characterized as aweb and is designated 14. The stretched web is received on an endlessconveyor 16 which carries it downwardly into a receptacle 18 containinga binder solution 20. An upper flattening roller 22 cooperating with theconveyor maintains the web in a flattened condition as it moves throughthe 3 binder liquid. As the wetted web leaves the conveyor it passesover a suction slot arrangement 24 where excess binder liquid isremoved. The web then is received by a second conveyor 26 which carriesit through a heating oven 28 and to a windup station where the finishedweb is wound into a roll 30.

During the expansion step the filaments are generally reoriented in lazytongs fashion so that in stretched form the web is greatly elongated andis narrowed in width. However, during the reorientation, the filamentsof the wetted stratum behave differently than the filaments of the drystratum. It is this difference in behavior that largely contributes tothe desirable character of the final web. Specifically, the filaments ofthe wetted stratum appear to have a greater tendency to cling togetheras if they had been wound in collected group form. In contrast, thefilaments of the dry stratum appear to rearrange themselves more likefilaments wound as individual, discrete filaments.

A finished web product derived from a mat composed of a single wetstratum and a single dry stratum is represented by FIGURE 4 which isintended to illustrate generally the variation in pattern of the twodiverse strata, with the web shown in delaminated form to emphasize thedifferences in pattern. The lower Web 32 corresponds to the stratumcomposed of dry filaments, and the upper web 34 corresponds to thestratum composed of wetted filaments. The wider lines of the stratum 34represent a substantial number of filaments which have generally behavedduring the stretching operation as a collected group of filaments byclinging together. The narrower lines of the stratum 34 indicateindividual filaments or small numbers of filaments which have shiftedduring stretching away from the filaments giving the collected groupappearance. In both cases, the degree of swirl or corrugation of thewetted stratum filaments appears to be distinctly greater than that ofthe filaments of dry stratum 32. The wetted stratum 34 also gives theappearance of an open-work structure having a substantial number ofvoids.

The filaments of the dry stratum 32 reorient themselves to provide anappearance of uniformity in which groupings of filaments are for themost part absent. That is, the stratum gives the appearance ofrelatively uniformly distributed individual filaments in which wavinessor corrugation of the filaments is largely lacking and generallyunnoticed. Thus the dry stratum well serves for background for thedistinctive pattern derived from the Wet stratum.

While as shown in FIG. 4 the separate strata of the finished web may beseparated for the most part by very carefully delaminating the strata,under normal handling the strata remain together.

For decorative purposes, it is desirable that the web not puff up, i.e.,expand in thickness, after passage through the dip tank and during itspassage through the oven 28. One way of preventing the puffing is towind mats which, when stretched, are relatively thin, such as less than50 mils th of an inch). With a thin mat, the weight of the liquidcomponent of the dip tank binder composition tends to hold the web fiatwhile the liquid component is being driven off in the oven, with thebinder solids progressively setting and holding the web in flat form asthe liquid is driven off.

It is of course important when a colored binder is applied to thefilaments on the drum that the subsequently applied dip tank binder havelight transmitting characteristics which permit the colored filaments toshow through. Since many conventional binders are substantiallytransparent, potential difiiculty in this respect is usually easilyavoided. For most applications a starch binder may be used in the tank18, in which case the dry stratum of the web has a generally whitishappearance with the wetted stratum providing a pattern of filaments ofthe desired color overlying the whitish background.

Since the filaments forming the wetted stratum 34 of the mat tend tocling together and thus emphasize their presence in the finished mat, itwill normally be found adequate to form the wetted stratum ofconsiderably fewer filaments than the filaments required in the drystratum 32. Thus as one example of a mat in which the distinct patternof the wetted stratum filaments is presented, the amount of glass usedto form the filaments of the wetted stratum is slightly less thanone-third of the amount of the glass used for form the filaments of thedry stratum.

While the description has been primarily concerned with the formation ofa filamentous mat in which the filaments are glass, the invention is notto be considered as restricted to glass filaments but includes filamentsformed of any organic or inorganic material which is susceptible tohandling in a process according to the invention.

The invention claimed is:

1. The method of making a filamentous mat, compris- (a) winding aplurality of filaments back and forth upon a rotating drum to form acylindrical compact filamentous mat of a series of overlying layershaving filaments in each layer lying in crossing relation to filamentsin adjacent layers;

(b) applying a binder to the filaments Wound in a selected portion,including at least one layer of filaments, of said mat while saidportion is being formed, so that said mat includes at least one layer ofbinder wetted filaments and at least one stratum of filaments which aredevoid of binder;

(c) slitting said cylindrical mat in a direction generally transverse tothe lay of said filaments and upwrapping the mat as a whole from saiddrum to form a planar compact mat;

(d) stretching said planar mat in a direction generally transverse tothe lay of said filaments to expand said mat; and,

(e) applying a binder to said expanded mat.

2. The method of claim 1 including:

(a) winding said plurality of filaments upon said drum in uncollectedform.

3. The method of claim 1 including:

(a) applying a binder to said filaments during winding having acoloration distinct from the coloration of said binder applied to saidmat in its stretched condition.

4. The method of claim 1 including:

(a) applying said binder during winding to less than half the filamentswound on said drum.

5. The method of making a filamentous mat, comprising:

(a) winding an inner stratum of a cylindrical compact filamentous mat bywinding a plurality of filaments back and forth upon a rotating drum toform said inner stratum of a series of overlying layers having filamentsin each layer lying in crossing relation to filaments in adjacentlayers;

(b) applying a binder during winding to the filaments forming said innerstratum;

(c) forming an outer stratum of said cylindrical compact filamentous matby winding a plurality of filaments back and forth upon said rotatingdrum to form a series of overlying layers having filaments in each layerlying in crossing relation to filaments in adjacent layers, without theapplication of a binder to the filaments forming said outer stratum;

(d) cutting said cylindrical compact mat formed of said inner and outerstrata in a direction generally transverse to the lay of said filamentsand upwrapping said cylindrical mat as a whole from said drum to form aplanar compact mat;

(e) stretching said planar mat in a direction generally transverse tothe lay of said filaments; and

(f) applying a binder to the filaments of both said inner and said outerstratum after said planar mat has been stretched.

6. The method of claim 5 including:

(a) applying a binder to said filaments of said inner stratum having acoloration distinct from the coloration of said binder applied to saidmat in i-ts stretched condition.

6 References Cited UNITED STATES PATENTS 2,505,045 4/1950 Holcomb156-174 X 2,609,320 9/1952 Modigliani 156-174 2,644,780 7/1953 Simkinset a1. 156-174 X 3,036,946 5/1962 Jackson 156-174 EARL M. BERGERT,Primary Examiner.

10 J. P. MELOCHE, Assistant Examiner.

1. THE METHOD OF MAKING A FILAMENTOUS MAT, COMPRISING: (A) WINDING APLURALITY OF FILAMENTS BACK AND FORTH UPON A ROTATING DRUM TO FORM ACYLINDRICAL COMPACT FILAMENTOUS MAT OF A SERIES OF OVERLYING LAYERSHAVING FILAMENTS IN EACH LAYER LYING IN CROSSING RELATION TO FILAMENTSIN ADJACENT LAYERS; (B) APPLYING A BINDER TO THE FILAMENTS WOUND IN ASELECTED PORTION, INCLUDING AT LEAST ONE LAYER OF FILAMENTS, OF SAID MATWHILE SAID PORTION IS BEING FORMED, SO THAT SAID MAT INCLUDES AT LEASTONE LAYER OF BINDER WETTED FILAMENTS AND AT LEAST ONE STRATUM OFFILAMENTS WHICH ARE DEVOID OF BINDER; (C) SLITTING SAID CYLINDRICAL MATIN A DIRECTION GENERALLY TRANSVERSE TO THE LAY OF SAID FILAMENTS ANDUPWRAPPING THE MAT AS A WHOLE FROM SAID DRUM TO FORM A PLANAR COMPACTMAT; (D) STRETCHING SAID PLANAR MAT IN A DIRECTION GENERALLY TRANSVERSETO THE LAY OF SAID FILAMENTS TO EXPAND SAID MAT; AND, (E) APPLYING ABINDER TO SAID EXPANDED MAT.